Hibernate二级缓存示例 [英] Hibernate second level cache example

问题描述

  @Entity 
 @Table（name =pizza） 
 public class Pizza实现Serializable {
 @Id 
 @GeneratedValue 
 private Integer id; 
私人字符串名称; 
私人双重价格; 
 
 public long getId（）{
 return id; 
} 
 
 public void setId（Integer id）{
 this.id = id; 
} 
 
 public String getName（）{
 return name; 
} 
 
 public void setName（String name）{
 this.name = name; 
} 
 
 public double getPrice（）{
 return price; 
} 
 
 public void setPrice（double price）{
 this.price = price; 
} 
 
} 
  

ehcache.xml

 < cache name =com.abp.osp.domain.Pizza
 maxElementsInMemory =100
 eternal =false
 timeToIdleSeconds =5
 timeToLiveSeconds =200/> 
< / ehcache> 
  

我在bean.xml中提到了ehcache

 < prop key =hibernate.cache.provider_configuration_file_resource_path> ehcache.xml< / prop> 
< prop key =hibernate.cache.use_second_level_cache> true< / prop> 
< prop key =hibernate.cache.use_query_cache> true< / prop> 
< prop key =hibernate.cache.region.factory_class> net.sf.ehcache.hibernate.EhCacheRegionFactory< / prop> 
< prop key =hibernate.cache.provider_class> net.sf.ehcache.hibernate.EhCacheProvider< / prop> 
  

以及我在dao类中的调用方法是

  Session session1 = sessionFactory.openSession（）; 
 
比萨pizza2 =（比萨）session1.load（Pizza.class，2）; 
 System.out.println（pizza2  - + pizza2.getName（））; 
 session1.close（）; 
 
会话session2 = sessionFactory.openSession（）; 
 
比萨pizza4 =（比萨）session2.load（Pizza.class，2）; 
 System.out.println（pizza4  - + pizza4.getName（））; 
 session2.close（）; 
  

输出结果为：

  Hibernate：select pizza0_.id as id0_0_，pizza0_.name as name0_0_，pizza0_.price as price0_0_ from pizza pizza0_ where pizza0_.id =？ 
 pizza2  - 薄壳
 Hibernate：选择pizza0_.id作为id0_0_，pizza0_.name作为name0_0_，pizza0_.price作为price0_0_从pizza pizza0_其中pizza0_.id =？ 
 pizza4  -  Thin Crust 
  

但它在数据库中击中了两次。我没有找到我的代码中有任何错误，请告诉我为什么它在数据库中击中了两次。

添加

  @Cache（usage = CacheConcurrencyStrategy.READ_ONLY，region =pizza）
  

在域名类中。

  @Entity 
 @Cache（usage = CacheConcurrencyStrategy.READ_ONLY，region =pizza）
 @Table（name =pizza）
 public class Pizza实现Serializable {
  

I am developing hibernate + ehcache program.

@Entity
@Table(name = "pizza")
public class Pizza implements Serializable{
    @Id
    @GeneratedValue
    private Integer id;
    private String name;
    private double price;

    public long getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

}

ehcache.xml

  <cache name="com.abp.osp.domain.Pizza"   
maxElementsInMemory="100"   
eternal="false"   
timeToIdleSeconds="5"   
timeToLiveSeconds="200" /> 
</ehcache>

I have mentioned ehcache in bean.xml

   <prop key="hibernate.cache.provider_configuration_file_resource_path">ehcache.xml</prop>
        <prop key="hibernate.cache.use_second_level_cache">true</prop>
        <prop key="hibernate.cache.use_query_cache">true</prop>
        <prop key="hibernate.cache.region.factory_class">net.sf.ehcache.hibernate.EhCacheRegionFactory</prop>
         <prop key="hibernate.cache.provider_class">net.sf.ehcache.hibernate.EhCacheProvider</prop>

and my calling method within dao class is

 Session session1=sessionFactory.openSession();  

          Pizza pizza2=(Pizza)session1.load(Pizza.class, 2);
          System.out.println("pizza2--"+pizza2.getName());  
          session1.close(); 

 Session session2=sessionFactory.openSession();  

          Pizza pizza4=(Pizza)session2.load(Pizza.class, 2);
          System.out.println("pizza4--"+pizza4.getName());  
          session2.close(); 

Output is:

Hibernate: select pizza0_.id as id0_0_, pizza0_.name as name0_0_, pizza0_.price as price0_0_ from pizza pizza0_ where pizza0_.id=?
pizza2--Thin Crust
Hibernate: select pizza0_.id as id0_0_, pizza0_.name as name0_0_, pizza0_.price as price0_0_ from pizza pizza0_ where pizza0_.id=?
pizza4--Thin Crust

But it hit twice in database.I don't find anything wrong in my code.Please suggest me why it hit twice in database.

解决方案

I have solved my question.I need to add

@Cache(usage=CacheConcurrencyStrategy.READ_ONLY,region="pizza")

In domain class.

@Entity
@Cache(usage=CacheConcurrencyStrategy.READ_ONLY,region="pizza")
@Table(name = "pizza")
public class Pizza implements Serializable{

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